With the rapid development of the Internet, network promotion more popular, and search engine became a customer to understand the enterprise website in the main way, cnnic survey report shows 80% website traffic from search engine, so enterprise web site aimed at search engine optimization is at present the enterprise compare common promotion mode. Seo is through understanding how all kinds of search engines to grab the Internet page, and how to determine how to conduct the index for a particular keyword search technology, such as the ranking outcome to the optimization of web pages related, make its improve your search engine ranking, thus improve site traffic, finally enhance website sales ability or advocacy capacity of technology. Seo is one way the search engine marketing, search engine marketing is one way of network marketing, network marketing is part of the website operation, website operation is the ultimate goal of profitably, so seo is designed to make web site for profit. This paper from the definition of seo, working principle, technical and cheating, finally through a web site case simple discusses the application in commercial websites seo.